MOLECULAR CHOREOGRAPHY OF TEMPORAL MEMORY: PREFRONTAL ERK1/2 SIGNALING REGULATES RECOGNITION MEMORY STABILITY IN MICE

Temporal order memory (TOM) allows organisms to distinguish the relative recency of events, a cognitive process vital for navigating complex environments. However, the molecular mechanisms that compose these memories remain poorly understood. In this study, we used a two-session TOM protocol that uncovered a critical window where a second training session occurring one hour after initial object presentation significantly impairs the stability of the first recognition memory.

To ensure high-resolution and unbiased quantification of these behavioral dynamics, we developed RAINSTORM¹ (Real and Artificial Intelligence for Neuroscience — Simple Tracker for Object Recognition Memory). This open-source, AI-driven tool leverages pose estimation data to automate precise behavioral labeling, allowing for a reproducible and comprehensive analysis of mouse exploration patterns that traditional manual scoring often overlooks.

Our molecular analysis revealed that TOM depends on specific activation of extracellular signal-regulated kinase 1/2 (ERK1/2) within the medial prefrontal cortex (PFC) (Fig 1A). Through pharmacological interventions via intra-PFC microinjections, we established that targeted inactivation of ERK1/2 was sufficient to mimic the interference effect. Conversely, preventing ERK inhibition via phosphatase blockade protects the memory trace (Fig 1B).

Altogether, these results identify prefrontal ERK1/2 kinetics as a key determinant for temporal memory stability and highlight the power of AI-driven behavioral analysis. We are currently evaluating transgenic mice to elucidate whether the TOM protocol established here is sensitive enough to detect early cognitive deficits associated with Alzheimer's disease, and how these relate to dysregulation of the ERK pathway.

1. D'hers et al. (2025) 10.1002/cpz1.70171.

Figure 1: Description in Alt Text.